1. Field of the Invention
The present invention relates to a system for preparing and managing manufacturing-process specifications, and particularly, to a system for preparing manufacturing-process specifications, capable of efficiently designing the conditions of individual manufacturing processes.
2. Description of the Prior Art
Manufacturing processes are manually designed by skilled engineers, and simulation is used only to supplement the engineers. Manufacturing-process specifications designed for, for example, a semiconductor large-scale integrated circuit device (LSI) must be edited and checked to see whether or not they are correct according to accumulated knowledge. Then, simulation is carried out according to the specifications, to test the structure of a semiconductor wafer, impurity distributions, and the characteristics of the LSI.
To assist these tasks, several systems have been developed and used in practice in, for example, an LSI manufacturing line. The LSI manufacturing line has a production control system that needs process specifications to specify and control apparatuses that work in the manufacturing line. The process specifications are huge to precisely control the manufacturing line and improve the quality and yield of products. To reduce manpower, time, and careless input mistakes in preparing the process specifications, an assisting system is used.
Also used to assist the preparation of the process specifications are process simulators, device simulators, and circuit simulators. These simulators simulate the manufacturing, electric characteristics, and circuit characteristics of LSIs, and such simulation work is essential before actually manufacturing LSIs to find the problems thereof.
Conventional production control systems control apparatuses for carrying out manufacturing processes according to specifications, independently of simulation. The simulation, however, must use actual manufacturing conditions, to determine or evaluate the manufacturing processes and the electric characteristics of products manufactured through the processes under various conditions. Instead of using every piece of data set for actual manufacturing processes, the conventional simulation uses only part thereof. For example, the prior art simulates a diffusion process only with specifications for charging and discharging a wafer into and from a diffusion furnace, as well as diffusion temperature, diffusion atmosphere, and diffusion time.
Simulation needs specific data such as discretization data for numerical calculations. Such simulation data qualitatively differs from process specification data. Due to this, a prior art of FIG. 1 employs a tool for converting process specification data into simulation data, and simulation data into process specification data. This prior art employs different databases for preparing the process specification data and simulation data. Namely, a database A stores data for a production control system and is used to prepare the process specification data, and a database B stores data for a simulation system and is used to prepare the simulation data. This kind of prior art is disclosed in, for example, Japanese Unexamined Patent Publication Nos. 9-34533 and 6-260380.
LSIs are integrating, adding more values, and improving yield and productivity. This tendency is heightening requirements for reduction in process variations and margins. It is important, therefore, to improve simulation accuracy so that a simulation result conforms to actual manufacturing processes. To faithfully simulate actual manufacturing processes, some prior art tries to adjust existing models of manufacturing processes to reflect actual conditions.
The prior art prepares models and parameters for every process. For example, the prior art prepares a model of impurity diffusion and parameters for a diffusion process according to diffusion temperature, time, and atmosphere.
In practice, each process involves variations due to apparatuses to carry out the process. For example, the operating conditions of a diffusion furnace are influenced by manufacturing variations specific to a heat source of the furnace and by changes in the flow rates and velocities of gases in the furnace. The prior art is incapable of considering these variations because the prior art fixes models and parameters for each process.
Specification data for each process contains data about apparatuses to carry out the process and data for controlling the apparatuses. When preparing simulation data from the specification data, the prior art does not usually pick up the data about apparatuses and data for controlling them.
In this way, the prior art handles the process specification data and the simulation data independently of each other, and therefore, must prepare different databases to store them. Process specifications are usually prepared for each process or for a process sequence, and an engineer is assigned to prepare specifications for a process sequence. An engineer of a given sequence prepares process specifications for the sequence, tests the specifications, and improves them through simulation. Sometimes, the engineer who tests the specifications of a given process sequence differs from the engineer who simulates the process sequence. To complete specifications for the process sequence, many pieces of specification data and simulation data are prepared and tested. These pieces of data are kept by the engineers in charge. When the other engineers want to have technical information such as process specification data, simulation data, prototype evaluation results, and simulation results, they must refer to the engineers in charge.
This hinders the quick transfer and sharing of information, to thereby deteriorate the efficiency of developing LSIs.
To share information, it is necessary to make a collective database of technical know-how and prototype evaluation results obtained from groups of manufacturing processes. Since the process specification data and simulation data of the prior art are separately prepared by engineers, the process specification data, data obtained from manufacturing processes that are based on the process specification data, simulation input data, and simulation resultant data have different formats. As a result, it is difficult to make a collective database of them.
Like the process specification data, the simulation data is based on production and simulation know-how. Accordingly, it is beneficial to make a database of the simulation data. Since the process specification data and simulation data are independent of each other, it is difficult for the prior art to combine them together and utilize them for new simulation.
An object of the present invention is to provide a system for preparing and controlling manufacturing-process specifications, capable of equally handling production control and simulation and effectively utilizing simulation results. The present invention also provides a method of preparing process data for the system, and a method of manufacturing semiconductor devices with the use of the system.
In order to accomplish the objects, the present invention provides a system for preparing manufacturing-process specifications. The system has a database for storing process data that includes manufacturing-process specifications applied to apparatuses to carry out manufacturing processes and parameters used to simulate the manufacturing processes; a production control system for controlling the apparatuses according to the process data, and collecting data measured through the manufacturing processes; a simulation system for simulating the manufacturing processes according to the process data; and an editing unit for correcting the parameters according to the collected data and amending the manufacturing-process specifications according to a result of the simulation.
The database may collect data for each of the apparatuses and be amended so as to reflect dependence among the apparatuses in carrying out the manufacturing processes.
The database may collect data for each apparatus of the same model and be amended so as to reflect dependence among the apparatuses of the same model in carrying out the manufacturing processes.
The database may consist of a process preparation database for storing the collected data and/or data to be corrected according to a result of simulation, a simulation database exclusive to the simulation system, and a production control database exclusive to the production control system.
The apparatuses may manufacture electronic parts.
The electronic parts may be semiconductor devices.
The process data may include common data serving as process specification data and simulation data. The common data may include process names classified in at least two categories and process conditions classified in at least two categories.
The system may further have an editing unit for editing process flow data that describes at least the sequence of manufacturing processes and the conditions of each of the manufacturing processes; and an editing unit for completing the process data by adding apparatus conditions and simulation conditions to the process data.
The production control system may have an editing unit for adding the names and conditions of apparatuses to the process data.
The simulation system may have an editing unit for adding a result of simulation to the process data.
The manufacturing-process-specification preparing system may further have a retrieval unit for retrieving necessary data from the process data with process conditions as retrieval criteria. The process data includes common data serving as process specification data and simulation data. The common data includes process names classified in at least two categories and process conditions classified in at least two categories.
The system may further have a storage unit for storing models and parameters for apparatuses that are simultaneously operated to carry out a manufacturing process so that the simulation system may use the models and parameters.
The present invention also provides a method of preparing manufacturing-process specifications. The method includes the steps of controlling apparatuses according to the manufacturing-process specifications, to carry out manufacturing processes; collecting data measured through the manufacturing processes; simulating the manufacturing processes according to corresponding models and parameters; correcting the models and parameters according to the collected data; and amending the manufacturing-process specifications according to a result of the simulation.
The method may employ a common database for the manufacturing processes and simulation.
The method may be applicable to manufacturing electronic parts.
The electronic parts may be semiconductor devices.
The common database employed by the method may contain common data serving as process specification data and simulation data. The common data may include process names classified in at least two categories and process conditions classified in at least two categories.
The common database employed by the method may contain at least process flow data, apparatus conditions, and simulation conditions. The process flow data describes the sequence of manufacturing processes and the individual conditions of the manufacturing processes.
The common database may contain the names and conditions of apparatuses.
The common database may contain simulation results.
The common database may contain process names classified in at least two categories and process conditions classified in at least two categories so that the process conditions may be used as retrieval criteria.
The present invention also provides a production control system having a database for storing data according to which the production control system controls apparatuses to carry out processes to manufacture electronic parts. The production control system collects data from the apparatuses through the processes and stores the collected data in the database so that the data in the database may reflect dependence among the apparatuses.
The database may collect data from each of apparatuses of the same model so that the data in the database may reflect dependence among the apparatuses in carrying out the processes.
In this way, the process data is used for the production control system as well as for the simulation system, and simulation results are efficiently used for developing products. The present invention easily makes an integrated database of manufacturing know-how and simulation know-how. The present invention simulates individual apparatuses with the use of models and parameters that have been prepared by considering the processing variations of the apparatuses.